Now that tax season is upon us, many immigrants are wondering whether or not they must file a U.S. tax return. The answer will depend upon your status, as you must usually file a tax return if you have been given permission to work here.

Those who hold green cards are considered permanent residents, and are normally required to file a tax return if they work in the United States. In addition, some immigrants may be required to file a tax return even though they are considered nonresident aliens.

The IRS has developed what it calls a “substantial presence test” to determine whether an alien is considered a tax resident. This substantial presence test is a complex formula that takes into account the number of days a person was present during the current year and the previous two years.

Nonresident aliens are required to file using 1040NR or 1040NR-EZ, which are tax forms designed especially for non-resident aliens. Resident aliens must use the same tax forms as U.S. citizens, and may file joint returns with a spouse who is also a resident alien or U.S. citizen. These individuals will also be able to claim many of the same deductions.

Immigrants who are required to file a tax return must do so by the filing deadline of April 15, or be subject to the same fines and penalties that a United States citizen would incur. Those who have questions about filing their taxes should speak with a tax professional, who can best advise them on which actions to take.